Anyone using KT88's in D series ARC gear?

It has been a long time since I owned my D70. ARC amps of that period have a limited range on their bias pots. So the answer is without modification, maybe. Turn the bias pots down and install the KT88s. See if you can turn the trim pots to the proper bias. I never tried KT88s in my D70. I did run them in my Classic 60 and a slight modifications needed to be made so that they could be biased.

The Speaker strips were always a problem. Though I think spades have gotten a little bigger over time. I used Audio Research speaker cables with my D70 so I had no problem. Excellent cables for the money with ARC equipment.

How are the 2 large Capacitors? If they have not been replaced they should be checked. They may need to be replaced soon.

Hi Lostbears, Thanks for the input. I think the two large Caps may need replacement as they are all original. The speaker strips seem designed for bare wire or? Anyhow, like you say they are a real problem. I will probably have someone replace those along with the cheap RCA's and the hardwired power cord.

Audio Research offered an upgrade to the Classic Series amplifiers which replaced 6550 output tubes with KT88 tubes. I believe the change over required a resister replacement in order to properly use the KT88 tube.

I would not change anything in your D-70 if it is not broken. I have owned ARC equipment much older than the D-70 which were still operating perfectly.

The barrier strips are not a problem. You just need the proper spades to fit the barrier strips. Why would you change the amp instead of the cable connectors?

The power cord is hardwired for a reason. It is a solid connection and the power cord was voiced by ARC for your amplifier.

The RCA connectors are not cheap. ARC used those connectors for years on some of the best sounding equipment ever made until the Tiffany style connectors came along. I have never heard of anyone complain about those connectors on a D-79B and I doubt that anyone has ever changed the power cord or barrier strip on that amp either.

You will only degrade the D-70 by making any changes. Buy some 6550s and enjoy the amp the way it was intended to be used. They will cost less than making the changes you mentioned.

Check around for smaller spades. I know someone like Audioquest or Cardas makes them.